Prevalence of silent myocardial ischemia in asymptomatic individuals with subclinical atherosclerosis detected by electron beam tomography

BACKGROUND: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis. METHODS AND RESULTS: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia. CONCLUSION: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD.     

电镜观察透明质酸酶对人眼晶状体上皮细胞作用

目的：探讨透明质酸酶是否可以溶解晶状体囊膜上皮细胞及其作用机制。方法。取人眼超声乳化白内障摘除术中撕下的前囊膜，对半切开，一半立即置于37℃水浴箱中的2ml平衡液中。另一半置于37℃水浴箱中的2ml平衡液 1500IU透明质酸酶中。分别放置5、1O、15min，然后立即放入4％戊二醛中固定，送透射电镜检查。结果：置于平衡液中5、10、15min的前囊膜，囊膜表面的晶状体上皮细胞之间的细胞连接完整;而置于透明质酸酶中5，10、15min的前囊膜，其表面的晶状体上皮细胞之间以及细胞与囊膜之间的缝隙随时间延长而增大。结论:透明质酸酶可以破坏晶状体上皮细胞之间以及细胞与囊膜之间的连接，从而使晶状体囊膜上的上皮细胞易于被清除。     

新疆出血热病毒与流行性出血热病毒的生物学特性比较

本文通过免疫荧光(IF)和电镜(EM)技术对新疆出血热(XHF)及流行性出血热(EHF)病毒的生物学特性在Vero E_6及LLC-MK_2两株传代细胞上进行了比较。两种病毒感染两株细胞后免疫荧光染色有两种不同的荧光形态特征,两种病毒对细胞的敏感性明显不同,XHF病毒在LLC-MK_2细胞上感染后6～8天可出现明显的细胞病变,而EHF病毒感染此细胞后则不引起病变。电镜观察到两种病毒在LLC-MK_2细胞中都能形成与布尼病毒相似的形态特征。     

冷冻(断裂)复型电镜技术的应用

本文简单介绍冷冻断裂复型电镜技术在国内、外的概况,並阐明了该项新技术的独特作用和具体的操作步骤;在制作生物样品时所需的仪器设备和试剂的配制等内容。     

The cholinergic innervation of the rat fascia dentata: identification of target structures on granule cells by combining choline acetyltransferase immunocytochemistry and Golgi impregnation

A monoclonal antibody against choline acetyltransferase (ChAT), the acetylcholine-synthesizing enzyme, was used to study cholinergic synapses on identified (Golgi stained) granule cells in the rat fascia dentata. Choline acetyltransferase immunocytochemistry was applied to 40-microns Vibratome sections cut perpendicular to the longitudinal axis of the hippocampus. Light microscopy revealed fine varicose ChAT-immunoreactive axons in all layers of the fascia dentata, i.e., in the stratum moleculare, the stratum granulosum, and the subgranular polymorph zone. Most fibers were observed in the vicinity of granule cell bodies where they ran mainly parallel to the granular layer. Next, the immunostained Vibratome sections were sandwiched between small pieces of Parafilm and piled to form a block that was covered with agar and Golgi stained. After that, the sections were separated by cutting away the agar and removing the Parafilm. Sections containing well-impregnated granule cells were gold-toned (Fairén et al., '77), embedded in Araldite, and subjected to ultrathin sectioning for electron microscopy. A total of 14 gold-toned granule cells were examined in the electron microscope for synaptic contacts with cholinergic afferents. Choline acetyltransferase-immunoreactive axon terminals were observed that established symmetric synaptic contacts with the cell bodies and dendritic shafts of the gold-toned identified granule cells. Two types of contact were observed on spines arising from gold-toned granule cell dendrites. Immunoreactive terminals established asymmetric synaptic contacts with the head of small spines and symmetric contacts with the stalk of large, complex spines. The boutons forming asymmetric synaptic contacts with the cup-shaped spine head of the complex spines were not found to be immunoreactive. Our results demonstrate that cholinergic fibers to the rat fascia dentata establish characteristic types of synaptic contact with different postsynaptic elements of granule cells, suggesting a complex function of this afferent system.     

吗啡成瘾性大鼠脑内核团神经细胞[Ca 2+]i变化的研究

目的 研究吗啡成瘾对大鼠脑内与成瘾相关核团神经细胞[Ca 2 ]i的影响.方法 将50只SD大鼠随机分成吗啡成瘾组和对照组,观察成瘾后的戒断症状;应用对Ca2 敏感的探针Fluo-3与Ca2 络合后被激光激发发出荧光的特性,利用激光共聚焦显微镜观察伏核、海马、内侧额前皮质神经细胞[Ca 2 ]i变化,并用图像分析软件进行处理.结果 吗啡成瘾大鼠脑内伏核、海马及内侧额前皮质神经细胞[Ca 2 ]i和对照组比较明显增高(P<0.01).结论 长期使用吗啡可明显增高伏核、海马和内侧额前皮质神经细胞[Ca 2 ]i.     

快速眼动睡眠剥夺后大鼠脑内神经元骨架蛋白及超微结构的变化

目的探讨经历不同时间快速眼动（REM）睡眠剥夺对大鼠皮质及海马各区神经元形态结构的影响。方法选择微管相关蛋白（MAP2）和神经丝（NF）作为正常神经元结构的标识物，利用免疫组织化学法和Western blot技术观察REM睡眠剥夺1、3、5、7 d4个时间点大鼠皮质及海马MAP2和NF表达的时空变化规律。同时运用电镜技术观察睡眠剥夺后神经元超微结构的变化。我们的实验是用改良的多平台睡眠剥夺模型进行REM睡眠剥夺，结合免疫组织化学染色技术和蛋白质电泳以及电镜超微结构分析。结果REM睡眠剥夺后5d大鼠皮质、海马CA1及齿状回神经元结构蛋白MAP2和NF表达较对照组明显减少（P〈0．05）；电镜神经元核仁偏位，胞质中出现少量肿胀的线粒体和内质网；部分神经轴突的髓鞘溶解与浓集。环境对照组、REM睡眠剥夺5d和7d组，皮质中超微结构改变的神经元所占比例分别为1．2％、3．6％和5．8％。结论REM睡眠剥夺能够导致大鼠脑内神经元的超微结构发生异常变化。     

Long-term survival in children under 3 years of age with low-grade astrocytoma

Objective The purpose of this study is to analyze clinical aspects and disease-free survival (DFS) in children less than 3 years of age diagnosed with low-grade astrocytoma. Methods In a period of 24 years (1980–2004), a total of 43 (5.4%) children were registered with these characteristics. Twenty-three patients had pilocytic astrocytoma, 18 diffused, and 2 mixed. Thirty-one (72.1%) children had incomplete surgical tumor resection and 12 (27.9%) had a complete tumor resection. Twelve (27.9%) patients had cranial radiotherapy and 17 (39.5%) received chemotherapy. Overall survival was recorded in 23 (53%). DFS was 50% at 250 months of follow-up for the whole group. DFS for the supratentorial group was 60% at 250 months, whereas, for the infratentorial, it was 22% at 120 months (p = 0.008). Conclusion The only favorable prognostic pattern was the supratentorial presentation. Radiotherapy and chemotherapy did not alter the outcome.     

UVA对人角质形成细胞的氧化损伤作用

①目的　探讨紫外线A(UVA)对人角质形成细胞氧化损伤的机制。②方法　用 5J/cm2 UVA照射角质形成细胞 ,酶生化法检测活性氧 (ROS)的含量及超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶 (GSH PX)活性的变化 ,流式细胞仪测定紫外线对角质形成细胞凋亡的影响 ,原位杂交技术观察 p2 1mRNA的变化 ,并与非照射组比较。③结果　与对照组比较 ,UVA照射组ROS含量升高 (t =113.6 8,P <0 .0 0 1) ,SOD、GSH PX活性下降 (t =5 7.2 3、19.0 4 ,P <0 .0 0 1) ,细胞凋亡率升高 (t=5 3.2 8,P <0 .0 0 1) ,p2 1mRNA表达增强。④结论　UVA对人角质形成细胞的损伤与氧自由基生成增多及细胞抗氧化能力抑制有关